Interview: Richard Stallman on the ethics of free software and fighting the mega-corporations...

Richard Stallman founded the free software movement nearly 30 years ago and is still campaigning for it todayPhoto: redjar

Imagine a world where you can tailor software to do whatever you want and pass that code on to other people who can change it again for their own use without any restrictions.

This is the world of free software that former MIT developer Richard Stallman and his supporters have been campaigning for since the 1980s.

Stallman founded the GNU project in 1984, which effectively launched the free software movement. As well as wanting to create a new Unix-like operating system, Stallman sought to promote freedom and ethical practices in the world of software development.

The addition of the Linus Torvalds' Linux kernel to the GNU project in 1992 formed the GNU/Linux operating system, which is now used by millions of computer users all over the world.

The GNU project was followed by the establishment of the Free Software Foundation in 1985, set up to promote freedom for computer users and defend the rights of those who use free software.

Stallman also pioneered the concept of copyleft, a licensing model in which programs can be freely used, modified and extended by others. The widely used GNU General Public Licence, published by the Free Software Foundation, is an example of a copyleft licence.

Nearly 30 years after founding the free software movement, Stallman is still campaigning for greater adoption of free software and against software patents and what he views as excessive copyright laws that restrict users.

Speaking to silicon.com, Stallman outlined the importance and progress of the free software movement but also the major obstacles that remain.

Free software vs open source: a difference in philosophy

One of the fundamental problems faced by the free software movement is that many people don't appreciate how it differs from open-source software, according to Stallman.

"The difference is tremendous and deep because it's at the level of values. Free software is software that respects your freedom and the social solidarity of your community. So it's free as in freedom. Price is just a side issue which we're not talking about. So think of free speech not free beer to understand what we're talking about," he explained.

The four freedoms that define free software are: to run the program as you wish, to study and change source code so it meets your needs, to redistribute exact copies to others and to distribute modified versions as you wish.

If a program fails to meet any of these criteria, it is "non-free proprietary user-subjugating software" because the restrictions imposed mean it controls the user rather than the other way around. The program is therefore an...